This post is outdated, please refer to https://www.lotharschulz.info/2025/12/25/bug-resolved-htaccess-trailing-slash-redirects-caused-wordpress-6-9-bug/

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WordPress 6.9 has a bug where post content silently fails to save in the Gutenberg editor — the save appears successful but content vanishes on refresh. Here’s how I diagnosed the issue and the workaround using Classic Editor until a fix is released.

The Problem

Post content wasn’t saving in WordPress — the save appeared successful (HTTP 200, “Post updated” message), but content was empty on refresh.

Solution/Workaround

Installed the Classic Editor plugin.

What seems an “easy” solution caused quite some trial and error plus swearing.

If you’re on WordPress 6.9, your saves appear successful but content vanishes on refresh, this one is for you.

Diagnostic Steps

1. First I checked browsers’ dev Network tab for API requests and http status codes. That ruled out failed requests.
2. Then I attempted to check the database directly via phpMyAdmin. I could confirmed post_content was empty while post_modified was updated. This proved the issue wasn’t caching or display-related.
   
3. I enabled WP_DEBUG logging and found deprecation notices but no fatal errors. That allowed me to rule out PHP crashes.sample line:
   [22-Dec-2025 08:07:22 UTC] PHP Deprecated: Optional parameter $file declared before required parameter $force is implicitly treated as a required parameter in /var/www/.../.../httpdocs/lotharschulz.info/wp-content/plugins/.../functions.php on line 123
4. Next, I switched to one of the default WordPress themes: Twenty Twenty-Four – the issue persisted. So it is very unlikely that a theme issue was the root cause.
5. I disbaled all plugins except the default ones – no change, the issue persisted.
6. I corralated timelines, last successful draft save was from Dec 8th. I updated to WordPress 6.9 Dec 12th. WordPress 6.9 could be the culprit
7. Finally I searched for known WordPress 6.9 bugs – amongst the search result set was also the official hotfix announcement that made me confirm: it’s a WordPress 6.9 bundled Gutenberg/block editor bug.

Solution/Workaround

After confirming the root cause, I (re)installed the Classic Editor plugin. Using this plugin, blog post draft content saves correctly.

Follow-up

I also filed a bug report at https://github.com/WordPress/gutenberg/issues/74158 — it’s already triaged and labeled as a bug.
I assume either the reported bug will be fixed or the next patch version update – likely 6.9.1 (expected in January 2025) – will fix the issue.

Related WordPress 6.9 Issues

I found these issues when search for the root cause of my problem. Not all of those are related, however that might be useful for similar issues with WordPress 6.9:

• https://make.wordpress.org/core/2025/12/12/wordpress-6-9-hotfixes/
• https://core.trac.wordpress.org/ticket/64368
• https://make.wordpress.org/core/2025/12/10/adjacent-post-navigation-changes-in-wordpress-6-9-and-compatibility-issues/

Environment Information

• PHP 8.3.28
• Plesk-managed shared hosting
• Chromium browser